WO2009090531A1 - Method for continuous conversion of copper matte - specification - Google Patents

Abstract

The industrial practice of converting copper matte comprises the oxidation of iron sulphide and subsequent oxidation of copper sulphide with the formation of copper blister, which is carried out discontinuously in Pierce-Smith or Hoboken converters. The present invention resolves said difficulty by making the industrial process a continuous operation. The method consists in the use of a continuous gravitational flow of copper matte to two reactors connected in series by a channel, in which oxidation and slagging of the iron in the copper matte is performed in the first reactor, followed by oxidation of the copper sulphide and formation of copper blister in the second reactor. Said intensive operation for converting liquid or liquid and solid copper matte is continuous and uses packed beds with a view to increasing the oxidation rate, in each reactor, with shorter operating times.

Description

 CONTINUOUS CONVERSION METHOD OF COPPER KILL

DESCRIPTIVE MEMORY

BACKGROUND.

The fusion of copper concentrate produces slag and slag. The copper matte is converted to blister copper in Peirce-Smith, Hoboken converters or continuous conversion processes, such as the Kennecott-Outokumpu, Mitsubishi or Noranda processes. The blister copper is directed to the fire refining process prior to the electro refining.

The classic discontinuous conversion process of copper matte is carried out in tilt furnaces called Peirce-Smith converters or tilt kilns with siphon gas outlet called Hoboken converter. The classic process is batch (batch) consisting of two stages: iron scorification and blister formation.

The first stage of the conversion is dedicated to the removal of FeS from the solution of Cu ₂ S-FeS, and scorching of iron oxides by the addition of siliceous flux.

[FeS] _kills + 1, 5O ₂ + SiO ₂ => (Fe ₂ SiO ₄ ) _and scoπa + SO ₂

The continuous conversion processes Mitsubishi and Kennecott-Outokumpu use lime as a flux, which forms ferritic calcium slag.

2 [FeS] _mat a + 3,5O ₂ + CaO => (CaO Fe ₂ O ₃ ) choose + 2SO ₂

After the removal of slag with subsequent blowing of air or enriched air, the precipitation of metallic copper (blister copper) is conducted.

[Cu ₂ S] _kills + O ₂ => 2 {Cu} _b | _lster + SO ₂

The classic conversion into a Peirce-Smith converter has the operational flexibility of a typical discontinuous process, low energy efficiency, high labor requirements and high sulfur dioxide emissions and volatile impurities. The fluctuation of Ia temperature and thermal shock shorten the life of the refractory, particularly in the nozzle area.

The dream of pyrometallurgists for continuous conversion processes came true in 1974 with the Mitsubishi process. In this high grade bush, it is continually converted into blister copper by oxidation in a bath with enriched air injected by lances located on the reactor roof. This is a stationary vertical cylindrical type. As a flux, lime is used for iron scorification. The biggest problem facing the Mitsubishi process is the corrosion of the refractory by the ferritic calcium slag with a high cuprous oxide content. 1 (1) S. Okabe and E. Kimura, "Injection metallurgy for continuous copper smelting and converting - Fundamental aspects of Mitsubishi process", The Howard Worner International Symposium on Injection Metallurgy "; (2) M. Nilmani and T. Lehner, eds., TMS, 1996, 83-96 .; S. Okabe and H. Sato, "Computer aided optimization of furnace design and operating condition of Mitsubishi continuous copper converter, Sulfide Smelting 98: Current and Future Practices, JA Asteljoki and R. L. Stephens, eds., TMS, 1998, 607-618 .; (3) H. Sato, F. Tanaka and S. Okabe, "Mechanism of refractory wear by calcium ferrite slag", EPD Congress 1999, B. Mishra, ed., TMS, 1999, 281-297 .; (4) M. Goto and M. Hayashi, "The Mitsubishi Continuous Process - Metallurgical Commentary", Second Edition, Mitsubishi Materials Corporation, June 2002 .; (5) M. Goto and M. Hayashi, "Recent advances in modern continuous converting", Yazawa International Symposium, Metallurgical and Materials Processing: Principies and Technologies, VoI. Il - High-temperature metais production, F. Kongoli et al, eds., TMS, 2003, 179-187.).

The continuous flash conversion process was developed by Outokumpu and Kennecott. This began industrially in 1996 at the Kennecott Foundry. The process uses the Outokumpu flash furnace for the oxidation of high grade powdered bush directly to blister copper. As a fluxing agent, lime is used which produces ferritic calcium slag with a high cuprous oxide content. The biggest advantage of the process

Kennecott-Outokumpu is the independence of the process of conversion of the concentrate fusion. The energy efficiency of the process is low due to heat losses due to

The solidification of the kills and the energy required for crushing and grinding the kills.

The major operational problem is the rapid corrosion of the refractory by the ferritic calcium slag with high content of cuprous oxide and production of a large amount of duct dust, from 9% to 11% of the feed. [(1) DB George, RJ. Gottling and CJ. Newman, "Modernization of Kennecott Utah copper smelter", COPPER 95 - COPPER 95 International Conference, VoI. IV - Pyrometallurgy of Copper, WJ. (Pete) Chen et al., Eds., The MetSoc of CIM, 1995, 41-52 .; (2) CJ. Newman, DN Collins and A J. Weddick, "Recent operation and environmental control in the Kennecott Utah copper smelter", Copper 99 - Copper 99 International Conference, VoI. V - Smelting Operations and Advances, DB George et al, eds., TMS, 1999, 29-45 .; (3) CJ. Newman and MM Weaver, "Kennecott Flash Converting Furnace design improvements - 2 - 1", Sulfide Smelting 2002, RL Stephens and HY Sohn, eds., TMS, 2002, 317-328 .; (4) D B. George, "Continuous copper Converting - A perspective and view of the future", Sulfide Smelting 2002, RL Stephens and HY Sohn, eds., TMS, 2002, 3-13 .; (5) R. Walton, R. Foster and D. George-Kennedy, "An update on flash converting at Kennecott Utah Copper Corporation", 2005 TMS Annual Meeting, Converter and Fire Refining Practices, A. Ross et al, eds., TMS, 2005, 283-294.].

The following continuous conversion process was started by the Noranda company in 1997. The Noranda Continuous Conversion process uses the Noranda reactor for the continuous oxidation of copper matte, keeping three layers inside the reactor: semi-blister, white metal and a scum. The use of siliceous flux produces phagetic slag saturated in magnetite. The process is not totally continuous. The semi-blister product requires the term of blowing in Peirce-Smith converter to obtain blister copper. The reactor needs frequent repair of the refractories, particularly in the nozzle area. At present the process is not in operation. [(1) PJ. Mackey, C. Harris and C. Levac, "Continuous converting of matte in the Noranda Converter: Part I Overview and metallurgical background", COPPER 95 - COPPER 95 International Conference, VoI. IV - Pyrometallurgy of Copper, WJ. (Pete) Chen et al., Eds., The MetSoc of CIM, 1995, 337-349 .; (2) CA. Levac et al., "Design and construction of the Noranda Converter at the Horne Smelter", Sulfide Smelting 98, Current and Future Practices, J.A. Asteljoki and R. L. Stephens, eds., TMS, 1998, 569-583 .; (3) Y. Prévost, R. Lapointe, CA. Levac and D. Beaudoin, "First year of operation of the Noranda continuous converter", Copper 99 - Copper 99 International Conference, VoI. V - Smelting Operations and Advances, D. B. George et al, eds., TMS, 1999, 269-282.].

The process of continuous conversion Ausmelt is under development. The process is carried out in the well-known vertical cylindrical Ausmelt reactor with lance. For the scorching of iron oxides, silica and lime are used, producing an olivine slag. [(1) J. Sofra and R. Matusewicz, "Ausmelt technology - Flexible, low cost technology for copper production in the 21 st century", Yazawa International Symposium, Metallurgical and Materials Processing: Principies and Technologies, VoI. Il - High-temperature metais production, F. Kongoli et al, eds., TMS, 2003, 211-226 .; (2) J. Sofra and R. Matusewicz, "Ausmelt technology - Copper production technology for the 21 st century", COPPER 2003 - COPPER 2003, VoI. IV - The Hermann Schwarze Symposium on Copper Pyrometallurgy, Book 1: Smelting Operations, Ancillary Operations and Furnace Integrity, C. Díaz et al, eds., The MetSoc of CIM, 2003, 157-172.].

BRIEF DESCRIPTION OF THE DRAWING.

Figure: is a schematic view in section, elevation and profile of the principle of the intensive pyrometallurgical method of continuous conversion of copper matte into two cascaded bed type reactors.

DESCRIPTION OF THE INVENTION

This invention relates to a pyrometallurgical method of continuous conversion of copper matte, which makes use of a flow of gravitational liquid matte through two reactors in series.

Thus, this invention leads to a continuous conversion method of copper matte consisting of the following steps:

Liquid copper mat (4) is transferred from a melting furnace through a channel to the first oxidation reactor (3) or solid matte load (6) directly on the surface of the bed packed in the first reactor;

Loading of solid fluxes (6) silica and lime, on the surface of the packed bed of the first reactor;

Dispersion and gravitational flow of liquid kills through a packed bed of ceramic grains;

Injection of air and oxygen enriched air through nozzles (2) in countercurrent to the flow of liquid kills rising inside the packed bed; Iron sulphide oxidation: [FeS] _kills + 1, 5O ₂ = * (FeOU _d0 + SO ₂ 3 [FeS] _ma ta + 5O ₂ => (Fe ₃ O ₄₎ + 3SO ₂ SOiIdO

Slag formation:

CaO + SiO ₂ => (CaSiO ₃ ) slag 2 (FeO) _only , _ldo + SiO ₂ => (Fe ₂ SiO ₄ ) _eS coria 2 (Fe ₃ O ₄ ) solid + [FeS] _kills + SiO ₂ => 3 (Fe ₂ SiO ₄ ) _is coria + SO ₂ (Fe ₃ O ₄ ) sώi¡do + CaO => (CaO.Fe ₂ θ3) β - «* a + FeO

Slag and white metal separation at the bottom of the reactor;

Continuous extraction of conversion slag through a bleed hole (1) and continuous extraction of white metal through a siphon or inclined hole;

Recycling of the slag conversion to the melting furnace or slag cleaning furnace;

Continuous transfer of white metal (copper sulfide) via channel (7) to a second copper sulfide oxidation reactor (9);

Dispersion and gravitational flow of white metal through a packed bed of ceramic grains;

Air injection or oxygen enriched air through nozzles (10);

Oxidation of white metal with blister copper formation: [Cu ₂ S] _kills + O ₂ => 2 [Cu] _bllster + SO ₂

Transfer of copper blister (1 1) via channel to fire refining;

Evacuation of the exhaust gases from the oxidation reactors of iron (5) and copper formation (8) to the general system for cleaning gases from the foundry and to the sulfuric acid plant. The principle of the process is schematically illustrated in Figure 1. The copper bush (4) dispersed in the surface of the ceramic bed flows down in the form of small drops and veins that come into contact with a flow of hot gases in countercurrent containing oxygen. An extremely high surface area ratio of liquid matte (4) with respect to its volume results in a high oxidation rate. Iron oxidation produces iron oxides that combine with fluxes to form slag. The parameters of oxidation, oxygen quantity and temperature can be precisely controlled by the flow of enriched air blown through the nozzles (2). Similarly, the dispersion of white metal (7) in the packed bed of ceramic grains of the second reactor increases the surface area of reaction that with the oxygen injected by nozzles (10) against the flow of liquid results in a very high rate oxidation of copper sulfide forming blister copper. The reactor temperature can be precisely controlled by the flow of injected air.

This invention has the following advantages compared to traditional copper matte conversion methods:

The investment costs are significantly lower due to the small size of the reactors for the same production capacity;

The labor requirements are lower due to the totally continuous mode of operation;

The safety conditions of the operators are improved as a result of the decrease in work exposed to high temperature;

A more precise process control due to the small inertia of the system. The degree of oxidation of the bush, temperature of the bush and slag can be precisely maintained in a narrow operating range;

There is no transport of liquid products by crane or formation of solid products to return to the process;

The degree of impurity removal is high due to the development of the surface area, which allows a better quality of blister copper; Fugitive emissions of sulfur dioxide and volatile impurities are drastically reduced due to the easy sealing of the reactors due to their stationary condition.

This invention has the following advantages compared to existing methods of continuous conversion of copper matte:

The investment costs are significantly lower due to the small size of the reactors for the same production capacity;

The continuity of the production can be ensured with two parallel lines of reactors, one in operation, the second in maintenance or waiting, thanks to the low cost of the construction of these;

The use of olivine slags saturated with MgO in the case of discarding bricks of magnesium chromium allows to reduce the corrosion of the refractory in the reactors; The use of nozzles injected oxygen enriched air directly into the porosity of the packed bed does not cause destruction of the refractory in the nozzle area;

A more precise process control due to the small inertia of the system. The degree of oxidation of the bush, temperature of the bush and slag can be precisely maintained in a narrow operating range;

EXAMPLE N ⁰ I.

73% copper - 75% Cu copper flows continuously through a channel from the bleeding hole of the Lieutenant Converter to the first oxidation reactor (3) at a rate of 20 t / h. 3900 Nm ³ / h of air are blown which are injected via nozzles (2) into the packed bed. On top of this, quartz flux, 0.68 t / h, and lime, 0.36 t / h, are continuously charged. The exhaust gases contain 11% SO ₂ and 5% O ₂ being continuously transferred to the gas cleaning system and acid plant. Slag (1) containing 6% Cu, 40% Fe, 15% CaO and 30% SiO ₂ is continuously bled at a rate of 2.4 t / h. White metal (7) flows from the siphon block at a rate of 18.3 t / h to a channel to the second copper sulfide oxidation reactor (9). In the latter the air blown, 13,800 Nm ³ / h enriched in oxygen (24% O ₂ ) is injected into the packed bed in countercurrent to the white metal. The outlet gas (8), 17,470 Nm ³ / h, containing 17.3% of SO ₂ and 5.2% of O ₂ is transferred to the gas cleaning system to the acid plant. The blister copper produced (11), containing 3000 ppm of O ₂ and 5000 ppm of S flows through a siphon block via channel to the copper fire refining furnace.

EXAMPLE N ⁰ 2.

Solid copper matte (73% - 75% Cu), with a grain size of 20 - 50 mm, is fed on the surface of the packed bed of an oxidation reactor (3) at a rate of 20 t / h along with fluxes, lime (0.36 t / h) and silica (0.68 t / h) (6). To the bed packed via nozzles (2) is blown air injected 2400 Nm ³ / h enriched in oxygen (85% of 02). The exhaust gases of this reactor (5) contain 80% SO ₂ and 4% O ₂ , being transferred to the gas cleaning system. Slag (1) containing 16% Cu, 33% Fe, 13% CaO and 30% SiO ₂ is continuously extracted at a rate of 2.6 t / h. White metal and copper blister (7), 16.1 t / h, flow through the siphon block into a channel towards a second reactor (9). It is blown through nozzles (10), 6750 Nm ³ / h, of oxygen-enriched air (24% O ₂ ) that is injected into the packed bed of ceramic grains. The outlet gas (8), 8920 Nm ³ / h, containing 18.4% of SO ₂ and 5.3% of O ₂ is transferred to the gas cleaning system and the acid plant. The blister copper produced (11), containing 3000 ppm of O ₂ and 5000 ppm of S flows through a siphon block via channel to the copper fire refining furnace.

Claims

1. Continuous intensive pyrometallurgical method of converting liquid copper matte into two reactors, CHARACTERIZED because it comprises the following successive stages: a.- feeding liquid kills continuously within the first oxidation reactor; wherein said reactor has a refractory chamber to contain said bush; wherein said refractory chamber contains a packed bed of ceramic grains or other chemically neutral grains; wherein said bush disperses and gravitationally flows through said packed bed; b.- simultaneously supplying gases containing air or oxygen enriched air through said packed bed of ceramic grains, in countercurrent to the liquid mat for the oxidation of iron sulfide; c- simultaneously supplying silicon fluxes, lime or mixtures thereof for the scorching of iron oxides and impurities with the formation of an olivine slag (CaO-SiO ₂ -FeO-Fe ₂ O ₃ ) conversion; in which it flows gravitationally through the porous bed; d.- continuously bleed conversion slag, from a bleeding hole, and copper sulphide, from a siphon block or inclined hole, from the oven floor; e.- continuously feed white metal to a second oxidation reactor in which said reactor has a refractory chamber to contain said white metal; wherein said refractory chamber contains a packed bed of ceramic grains or other chemically neutral grains; wherein said white metal disperses and flows gravitationally through said packed bed; f.- simultaneously supplying gases containing air or oxygen enriched air through said packed bed of ceramic grains, in countercurrent to the liquid white metal for the oxidation of copper sulphide with blister copper formation; in which it flows gravitationally to the bottom of the reactor; g.- continuously bleed copper blister from a siphon bleeding block or inclined hole from the oven floor; and h.- continuously evacuate the SO ₂ rich gases from the iron oxidation and copper formation reactors towards the sulfuric acid plant. 2. Method according to claim 1, CHARACTERIZED because the copper matte in (a) can be solidly charged onto the surface of the packed bed of the first reactor and melted with the hot gases that rise through the bed. 3. Method according to claim 1, CHARACTERIZED in that the copper matte in (a) can be charged in liquid form and simultaneously receive solid matte charge on the surface of the packed bed of the first reactor. 4. Method according to claim 1, CHARACTERIZED in that the oxygen enriched air in (b) of the blowing air varies from 21% to 80% depending on the heat losses of the reactor, grade of the matte and solid or liquid feed to ensure an autogenous process. 5. Method according to claim 1, CHARACTERIZED because as a flux in (c) only lime is added leading to the formation of ferritic calcium slag. 6. Method according to claim 1, CHARACTERIZED because as a flux in (c) lime, grease and quartz are added leading to the formation of an anortite slag (CaAI ₂ Si ₂ O ₈ ). 7. Method according to claim 1, CHARACTERIZED because in (a) it is possible to load on the surface of the packed bed remains of solid copper and high-grade copper returns, melted by the countercurrent process gases and collected by the metal white and the scum. 8. Method according to claim 1, CHARACTERIZED in that the oxygen enriched air in (f) of the blowing air varies from 21% to 80% depending on the heat losses of the reactor.